https://cspinet.org/tip/too-much-pho...t-your-kidneys
https://www.google.com/search?q=top+...gdnd3Mtd2l6EAw
As people age, there's a tendency for kidneys to lose their filtering ability. In the U.S., the average person, somewhere around late 70s to early 80s, is at stage 2 kidney Disease. Stage two is said to be mild. There are 5 stages, stage 5 being kidney failure.
Consuming too much potassium or phosphorus could affect your kidneys and your health overall . So it would help to know what foods contain high amounts. Potassium is listed on the ingredient label of the foods we eat, but phosphorus is not, and food companies are allowed to add phosphates to various foods.
So the question is: Why does the FDA allow food companies to add phosphates to processed foods and not report it on the ingredient label? The second link above will tell you the foods that naturally contain the highest amounts of phosphorus. But, according to the first link, there's no way of knowing how much is added to processed foods.
Final note: The greatest burden on kidneys usually comes from overconsuming animal protein. The average American eats about double the amount needed. And authors of high protein diet books will never tell you their diet is high in protein.